Not quite IRC, G+, or Roll20, but I've been thinking for a while about whether it would be good/bad/indifferent to place more emphasis on the abstract nature of D&D combat.

It would be possible to resolve most combats with just one set (or relatively few sets) of instructions from each player. The ref could go away and resolve the whole combat in one go, and then post a summary of the main events and the overall outcome, rather than the typical blow by blow account we're more accustomed to.

A combat would certainly be resolved very quickly--but perhaps it might all be over too quickly. Especially in the event that it goes badly for the players

I like the speed of that method, WOTE, but I don't like losing the ability to adjust actions on the fly, should something give reason for a drastic change of plans.

I was in a group that PbPd most of a game, then used Google Hangout to resolve the main combat.

It had mixed results. I'm not by any means socially inept, but... it is certainly easier to communicate clearly and concisely via text where when you have four guys chatting into video cameras a lot of time gets wasted... You would think it would go faster, but... maybe not.

Unseen Servant has a chat room function. I'd like to try something where we run a combat in the chat and the rest of the game in the forum.

My only experience with these kinds of methods was 3rd Edition first using openrpg and then just IRC + a hand rolled bot [aka eAsp]. Never tried the newer forms of this roll20 and the rest. They sound cool but it seems like you need to be able commit a block of time without interruptions. The PBP format or email chain is great because you can pause, do the dishes, help with homework, etc... No one gets annoyed.

With OD&D combat I'd say you easily resolve one in a day via PBP so long as most of the players were willing to check the boards that day multiple times. In the TEOWS game I've exceeded the normal posting rating for combats several time because every seemed to be around.

I fear not resolving round by round though. As a player I want round by round control, because you never know. The "throw the staff" to Dorgan move was an example of mid combat change of tactics. Without that ability things can go badly. As DM I do not want to make too many choices for the players because it seems like it would be taking some of the fun away from them.

I can deal with combat taking a long time when it's as exciting as, say, the battle we just had with the worgs and goblins. That encounter actually happened pretty quickly (at least by Hinterlands standards) because we all knew our characters' lives were on the line and so we were pretty close to a round per day rate of activity.

Maybe that's the choice you need to make with a game: either make sure that combat is deadly and all the PCs are fully invested, so they check in daily until it's resolved, or else put the emphasis of the game on other things, and let the DM handle the combat by himself, with only some previously agreed upon tactics from the PCs.

Or... going back to Mike's comments, you could agree to have the players be "available" one day or one night for multiple posts. Say you were going to run six rounds of combat between 1 PM and 3 PM that afternoon. DM was going to resolve a round every 30 minutes. You don't have to sit there the whole time, you just put in your actions and do something else for 30 mins until the next DM post was up. Puts a burden on the DM but you get combat out of the way pretty damn quickly.

Downside to that is there's very little time for coordinating actions but maybe that reflects the chaos of an actual battle. You can't stop in the middle of a sword duel and ask the Mage where to stand to avoid being burned by his Fireball. That should have been worked out before you ever set foot on the battlefield.